Planar and Pyramidal Tetracoordinate Carbon in Organoboron Compounds

• Published in: Journal of organic chemistry Vol. 70; no. 17; pp. 6693 - 6704
• Main Authors: Minyaev, Ruslan M, Gribanova, Tatyana N, Minkin, Vladimir I, Starikov, Andrey G, Hoffmann, Roald
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 19.08.2005
• Subjects: B derivatives; Chemistry; Exact sciences and technology; Organic chemistry; Organometalloidal and organometallic compounds; Preparations and properties; Pyramidal shape; Density functional method; Organic boron compounds; Boron Organic compounds; Molecular structure; Planar molecule
• ISSN: 0022-3263; 1520-6904
• DOI: 10.1021/jo050651j

Using previously proposed C(BH)2(CH)2 (16, 17) and C(CH)2B2 (22) systems with a central planar tetracoordinate carbon (ptC) atom linking two three-membered rings as building blocks, a series of stable structures containing two and three ptC centers within a molecule have been designed and computationally studied with the DFT (B3LYP/6-311+G**) method. Inclusion of a carbon atom ligated with π-accepting and σ-donating boron centers into at least one aromatic ring is critical for stabilization of a planar structure. A square pyramidal configuration at tetracoordinate carbon may be achieved in appropriately strained molecules such as [3.3.3.3]tetraborafenestrane 45 and others by surrounding the carbon with boron-centered ligands.